Wire Rope
Elevator wire rope consists of a core and several steel wires, connecting one end to the elevator cabin and the other to the counterweight. This rope moves simultaneously with the cabin and the counterweight, transmitting the driving force from the motor to the wire rope to move the elevator cabin.
Elevator wire ropes are precisely engineered and typically made from steel or other composites. These ropes usually have multiple strands of varying diameters twisted together, rather than individual, separate wires.
In traction elevators, wire ropes play a crucial role in connecting the counterweight and the cabin. By using the motor sheave and generating the necessary friction, they enable the movement of the cabin and the counterweight.
Structure of Elevator Wire Rope
Elevator wire rope consists of several wire strands twisted around a central axis, known as the core. These wire strands comprise several wire filaments twisted together, giving the wire rope a helical appearance.
The core of the wire rope plays a vital role in maintaining and supporting the wire strands, especially under heavy load and pressure conditions. The core is usually made from steel, hemp, or other natural fibers. A steel core provides greater strength to the wire rope, while a hemp core offers higher tensile strength. However, in most cases, the core of the wire rope is made from hemp.
Types of Elevator Wire Ropes
Elevator wire ropes can have different functionalities depending on their material, weave or lay type, and
Types of Wire Ropes Based on Wire Material:
- Uncoated Steel Wire: These ropes are unsuitable for humid environments and are best used with low humidity. They lack a coating and are prone to rusting.
- Stainless Steel Wire: If you need wire rope for a hot and humid environment, this type offers good resistance to heat and rust, making it a suitable choice.
- Galvanized Steel Wire: As the name suggests, these ropes are designed for environments with high humidity and a high risk of rust. The galvanized coating provides resistance to rust.
Types of Wire Ropes Based on Weave and Lay:
The weave of the wire strands in a wire rope is crucial to prevent them from unraveling. In the elevator industry, two common weaves are “regular lay” and “lang lay,” both of which can be right-hand or left-hand. However, regular lay is more common. Other weaves include standard, sealed, and Warrington.
- Standard Weave: In this type of weave, the wires have the same diameter, which gives the wire rope high flexibility.
- Seale Weave: Ropes with sealed weave have outer wires with a larger diameter than the inner wires, enhancing abrasion resistance.
- Warrington Weave: This weave uses wires of varying diameters alternately, providing greater resistance compared to sealed weave.
The operation of traction elevators relies on the driving force and wire ropes. Traction elevators have a simple system comprising a motor sheave and an idler sheave. The wire rope setup is such that one end is attached to the elevator cabin, and the other end to the counterweight. The wire rope passes over the idler sheave and the motor sheave, ensuring that when the cabin moves up, the counterweight moves down, and vice versa, facilitating easier cabin movement.
- High-Tensile Traction Wire Rope: This type is used when the elevator needs to move at high speeds or in tall buildings where the elevator is subject to significant wear.
- Iron Wire Rope: This type of wire rope can be used in almost all elevator applications.
Belt
A flat steel belt coated with polyurethane, developed by Otis’ New Technologies unit, has replaced the traditional round wire rope. Despite being only about 3 millimeters thick, these belts are significantly stronger than wire ropes.
Steel Belt with Polyurethane Coating: Using these flat steel belts coated with polyurethane eliminates concerns about “sheave and wire rope wear” due to constant friction, and they do not require special lubrication like wire ropes. This feature is one of the environmental benefits of steel belts.
These belts provide an exceptionally smooth and quiet movement for elevators. This unique technology delivers quiet, smooth, and vibration-free operation, offering a comfortable and silent ride for elevator passengers.
Steel belts with polyurethane coating reduce the need for components related to wire rope installation and occupy less space inside the elevator shaft. This allows for more safety and space for installers, service technicians, and repair personnel to work within the elevator shaft.
Elevator Wire Rope Lubrication
Lubricating elevator wire ropes is essential to prevent rust, reduce friction, and ensure smooth movement over the motor sheave and idler sheave. Regular and periodic lubrication extends the lifespan and durability of wire ropes. While lubrication is typically performed during installation, it should also be repeated regularly thereafter.
It is best to lubricate at points where the wire rope strands are more open, allowing the lubricant to penetrate deeply into the strands.
The ideal time for lubrication is when the wire rope rotates over the motor sheave and idler sheave. This movement helps distribute the lubricant evenly across the rope.
The lubricant used must have high penetration capabilities to cover all internal parts and external surfaces of the wire ropes, providing comprehensive rust protection.
The frequency of lubrication depends on environmental contamination levels, the elevator’s usage, and other conditions. Regular inspection will help determine the optimal lubrication schedule.
Avoid excessive lubrication, as too little friction can cause the ropes to slip. Additionally, excess oil can attract more dust, leading to increased wear and tear on the ropes.
Regular maintenance, including proper lubrication, ensures the safe and efficient operation of elevator wire ropes while prolonging their service life.
Material of Elevator Wire Ropes
Elevator wire ropes are made from intertwined strands, which can be either uncoated or non-galvanized steel, making them prone to rust. Alternatively, these strands can be made from galvanized steel, providing a protective coating that prevents rust, ideal for use in humid climates. There are also stainless-steel wire ropes, which are highly resistant to rust and heat, offering excellent durability.
Wire ropes also have a core, typically made from hemp, and constructed from natural or synthetic fibers. Although natural fibers are often used, synthetic fibers like polypropylene can also be used for the core. Another type of core is the steel core, where the metal strands of the wire rope are twisted around a steel core.
Application of Number 10 Elevator Wire Rope
One of the most commonly used elevator wire ropes is the number 10 wire rope, which can have either a hemp or steel core. If the core is hemp, the wire rope weighs approximately 34.6 kilograms per 100 meters. If the core is steel, it weighs around 42.2 kilograms per 100 meters. The number 10 wire rope with a hemp core is more flexible and is primarily used in elevators with a 1:1 roping system.
Application of Number 8 Elevator Wire Rope
Number 8 elevator wire ropes are known for their high durability, experiencing less wear and elongation compared to other wire ropes. These ropes are used in various industries and, due to their strength, sustain less damage over time. Using number 8 wire ropes enhances the lifespan and durability of other components, improves the elevator’s performance, and increases safety. This type of wire rope is commonly used in elevators with a 2:1 roping system and comes in three core types: hemp, semi-steel, and steel.
Reason for Using Hemp Core in Wire Ropes
The hemp core in wire ropes, whether made from natural or synthetic fibers, increases the flexibility of the wire rope. This characteristic is less pronounced in wire ropes with a steel core. Elevator wire rope is one of the mechanical and active components in an elevator, transferring the motor’s driving force to move the elevator cabin. The lifespan of an elevator wire rope depends on several factors, including how well it is serviced and maintained, the material of the wire, and the type of core used. On average, the lifespan of an elevator wire rope ranges between 5 to 10 years.
